I've realized now It's certainly not out of the realm of possibility that it's Cabe I now kind of see that as an alternative to her. You sort of showed me that when you suggested Justine. I still believe it will be Jan but you've talked me out of being certain. I still know she's in Avengers 2... but that doesn't mean she's definitely in this film so I may have trusted the wrong people about who she is. Something Wardell said in the interview makes sense now. He actually said he personally believed she was Bethany. Now I kind of get how that might work with a news angle and be connected to the plot. Maybe she's the ex gf and she came to check in on Stark/torment him and then gets involved in the plot, she would work better undercover. Still could be wrong, so I'll change my position.
Highly certain she'll be Wasp, but really she could be Cabe, or someone else. Could be a reporter, I definitely see the validity there. Though I believe Wasp and Cabe are more probable than anyone else when you consider all the context. If they're covering her up for a reason.
The justine hammer angle could even be there.

Why cover her up if there isn't some sort of secrecy to her role?
She's in the trailer and seems like a part of the movie and not really some random girl, so why not reveal her character? We know many other characters that give the plot away, so there has to either be something more. Or nothing like you say. But if it is nothing why include it in the trailer? She does look at least kind of serious about what evers happening maybe there is real attraction there? If she shows up as Bethany Cabe, his exgirlfriend, that might explain a little.

Inductive reasoning is based on a guessing game, but derived from specific facts.

It allows for the conclusion to be false even if the premises are true...

For example an inductive assumption is

If all lifeforms we know depend on liquid water to exist,
Then there's a very good chance that all life needs water to exist.

However, as you can see the conclusion could be false but is likely true...

Bethany Cabe certainly makes sense, too, and I'd be willing to place a few bets on Szostak playing that role. I'd also consider Contessa Valentina Allegra de Fontaine and Madame Hydra/Viper (as opposed to The Wolverine's bizarre take on her) as long shots, too.

About the "mystery" and "secrecy," though: I don't think there's necessarily any there at all. It's just a case that no interviewer has actually approached Szostak and asked her point blank who she was playing or what she was doing in the movie, and she's not an important enough role for Marvel to make an announcement. Again, just like Leslie Bibb and Olivia Munn.